Dmitri Mendeleev is usually credited with writing the periodic table in 1869. He organized the elements by atomic weight and, importantly, left gaps for elements that had not yet been discovered.

Why he gets credit

Mendeleev’s version became the basis of the modern periodic table because it correctly predicted properties of missing elements. Later discoveries, like gallium, scandium, and germanium, matched his predictions and helped confirm his work.

Other contributors

He was not the only scientist working on the idea. John Newlands, Julius Lothar Meyer, and others also developed earlier systems for organizing the elements, but Mendeleev’s table was the most successful and influential.

In plain terms

So the short answer is: Dmitri Mendeleev wrote the periodic table people usually mean today.